1. Field of the Invention
The present invention relates to a method of connecting a wire to a press-connecting terminal and a wire press-connecting apparatus. More particularly, the present invention relates to an improved method of connecting a wire to a press-connecting terminal and an improved wire press-connecting apparatus, in which the cutting (or shaving) and severance of a conductor in the wire are prevented when the sheathed wire is press-fitted into a slot (or gap) between press-connecting blades of the press-connecting terminal.
The present application is based on Japanese Patent Application No. Hei. 10-221692, which is incorporated herein by reference.
2. Description of the Related Art
When connecting a sheathed wire to a press-connecting terminal, a conductor in the wire can be connected to the terminal without the need for peeling a sheath from an end portion of the sheathed wire, and therefore the press-connecting terminal is suited for an automated operation, and also can reduce the fabrication cost. The press-connecting terminal 30, disclosed for example in Unexamined Japanese Patent Publication No. 10-92480, will now be described with reference to FIG. 4. This press-connecting terminal 30 is formed by bending a single metal sheet, and includes a contact 31, formed at one longitudinal end portion thereof for electrical connection to a mating metal terminal (not shown), pairs of opposed press-connecting blades 33, which are formed by inwardly bending parts of opposite side walls of a cross-sectionally U-shaped terminal body, and can cut a sheath 41 of the sheathed wire 40 to come into electrical contact with a conductor 43 of the wire upon press-fitting of the sheathed wire 40 into the slot between the press-connecting blades 33, and a wire holding portion 35 which is formed at the other longitudinal end portion of the terminal in adjacent relation to the press-connecting blades 33, and has its opposite side walls which can be bent inwardly to clamp the sheath 41, thereby fixedly connecting the sheathed wire 40 to the terminal.
In the above publication, as shown in FIG. 5, the press-connecting terminal 30, to which the wire is not yet connected, is beforehand mounted in each of juxtaposed terminal receiving chambers 45 in a connector housing 43, and then the sheathed wire 40 is disposed above the press-connecting terminal 30. In this condition, a lower die (anvil) 47 is inserted into a lower position corresponding to the wire holding portion 35, and a mounting jig (punch) 49 is moved downward from an upper position. As a result, the sheathed wire 40 is press-fitted into the slot between each pair of press-connecting blades 33, and at the same time the wire holding portion 35 is pressed to clamp or hold the sheath 41, thereby electrically connecting the sheathed wire 40 to the press-connecting terminal 30.
Thus, the mounting jig 49 is usually provided with a press-connecting punch for press-fitting the wire, and a clamping punch for fixing the wire, and simultaneously with the press-fitting of the sheathed wire 40 into the slot between each pair of press-connecting blades 33, the pressing of the wire holding portion 35 is effected.
With the use of such a mounting jig 49, the wire connecting-process in the automated operation was simplified, and also the time, required for the connecting operation, was reduced, so that the sheathed wire 40 could be efficiently connected to the press-connecting terminal 30.
However, in the wire connecting method and the wire press-connecting apparatus, using the above mounting jig, the wire holding portion 35, performing the function of strain relief, is pressed (as shown in FIGS. 7A and 7B) simultaneously with the press-fitting of the sheathed wire 40 into the slot between each pair of press-connecting blades 33 as shown in FIGS. 6A and 6B, and therefore the following difficulty has been encountered. When the wire 40 is press-fitted into the slot between the opposed press-connecting blades 33, the opposite (right and left) side walls are slightly deformed to be spread out (moved away from each other) as shown in FIG. 6B. On the other hand, bending forces, pressing the wire holding portion 35, are exerted inwardly, that is, in directions opposite respectively to the direction of the above outwardly-deforming forces, and prevent the opposite (right and left) side walls from being spread out. Particularly, those press-connecting blades 33, disposed close to this portion, is much affected by these bending forces, and therefore the conductor of the sheathed wire, press-fitted into the slot between these press-connecting blades, is liable to be severed. Namely, the opposed press-connecting blades are not smoothly spread out in accordance with the press-fitting of the sheathed wire, and in this condition the sheathed wire is almost forcibly press-fitted into the slot between the press-connecting blades.